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The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

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<h4><a name = "tag_001_014_909">&nbsp;</a>NAME</h4><blockquote>
hash - remember or report utility locations
</blockquote><h4><a name = "tag_001_014_910">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

hash <b>[</b><i>utility</i>...<b>]</b>

hash -r 
</code>
</pre>
</blockquote><h4><a name = "tag_001_014_911">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>hash</i>
utility affects the way the current shell environment
remembers the locations of utilities found as described in
<xref href=cmdsea><a href="chap2.html#tag_001_009_001_001">
Command Search and Execution
</a></xref>.
Depending on the arguments specified, it adds utility
locations to its list of remembered locations
or it purges the contents of the list.
When no arguments are specified,
it reports on the contents of the list.
<p>
Utilities provided as built-ins to the shell
are not reported by
<i>hash</i>.
</blockquote><h4><a name = "tag_001_014_912">&nbsp;</a>OPTIONS</h4><blockquote>
The
<i>hash</i>
utility supports the <b>XBD</b> specification, <a href="../xbd/utilconv.html#usg"><b>Utility Syntax Guidelines</b>&nbsp;</a> .
<p>
The following option is supported:
<dl compact>

<dt><b>-r</b>
<dd>Forget all previously remembered utility locations.

</dl>
</blockquote><h4><a name = "tag_001_014_913">&nbsp;</a>OPERANDS</h4><blockquote>
The following operand is supported:
<dl compact>

<dt><i>utility</i><dd>The name of a utility to be searched for and added
to the list of remembered locations.
If
<i>utility</i>
contains one or more slashes, the results are unspecified.

</dl>
</blockquote><h4><a name = "tag_001_014_914">&nbsp;</a>STDIN</h4><blockquote>
Not used.
</blockquote><h4><a name = "tag_001_014_915">&nbsp;</a>INPUT FILES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_916">&nbsp;</a>ENVIRONMENT VARIABLES</h4><blockquote>
The following environment variables affect the execution of
<i>hash</i>:
<dl compact>

<dt><i>LANG</i><dd>Provide a default value for the internationalisation variables
that are unset or null.
If
<i>LANG</i>
is unset or null, the corresponding value from the
implementation-dependent default locale will be used.
If any of the internationalisation variables contains an invalid setting, the
utility will behave as if none of the variables had been defined.

<dt><i>LC_ALL</i><dd>
If set to a non-empty string value,
override the values of all the other internationalisation variables.

<dt><i>LC_CTYPE</i><dd>
Determine the
locale for the interpretation of sequences of bytes of text data as
characters (for example, single- as opposed to multi-byte characters
in arguments).

<dt><i>LC_MESSAGES</i><dd>
Determine the locale that should be used to affect
the format and contents of diagnostic
messages written to standard error.

<dt><i>NLSPATH</i><dd>
Determine the location of message catalogues
for the processing of
<i>LC_MESSAGES .
</i>
<dt><i>PATH</i><dd>Determine the location of
<i>utility</i>,
as described in
the <b>XBD</b> specification, <a href="../xbd/envvar.html"><b>Environment Variables</b>&nbsp;</a> .

</dl>
</blockquote><h4><a name = "tag_001_014_917">&nbsp;</a>ASYNCHRONOUS EVENTS</h4><blockquote>
Default.
</blockquote><h4><a name = "tag_001_014_918">&nbsp;</a>STDOUT</h4><blockquote>
The standard output of
<i>hash</i>
is used when no arguments are specified.
Its format is unspecified, but includes
the pathname of each utility in the list of remembered locations
for the current shell environment.
This list consists of those utilities named in previous
<i>hash</i>
invocations that have been invoked,
and may contain those invoked and found through the
normal command search process.
</blockquote><h4><a name = "tag_001_014_919">&nbsp;</a>STDERR</h4><blockquote>
Used only for diagnostic messages.
</blockquote><h4><a name = "tag_001_014_920">&nbsp;</a>OUTPUT FILES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_921">&nbsp;</a>EXTENDED DESCRIPTION</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_922">&nbsp;</a>EXIT STATUS</h4><blockquote>
The following exit values are returned:
<dl compact>

<dt>0<dd>Successful completion.

<dt>&gt;0<dd>An error occurred.

</dl>
</blockquote><h4><a name = "tag_001_014_923">&nbsp;</a>CONSEQUENCES OF ERRORS</h4><blockquote>
Default.
</blockquote><h4><a name = "tag_001_014_924">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
Since
<i>hash</i>
affects the current shell execution environment,
it is always provided as a shell regular built-in.
If it is called in a separate utility execution environment,
such as one of the following:
<pre>
<code>
nohup hash -r
find . -type f | xargs hash
</code>
</pre>
it will not affect the command search process of the caller's environment.
<p>
The
<i>hash</i>
utility may be implemented as an alias, for example,
<i><a href="alias.html">alias</a></i>
<b>-t -</b>,
in which case utilities found through normal command search
will not be listed by the
<i>hash</i>
command.
<p>
The effects of
<i>hash</i>
<b>-r</b>
can also be achieved portably by resetting the value of
<i>PATH ;
</i>in the simplest form, this can be:
<pre>
<code>
PATH="$PATH"
</code>
</pre>
<p>
The use of
<i>hash</i>
with
<i>utility</i>
names is unnecessary for most applications,
but may provide a performance improvement
on a few implementations; normally, the hashing
process is included by default.
</blockquote><h4><a name = "tag_001_014_925">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_926">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_927">&nbsp;</a>SEE ALSO</h4><blockquote>
<xref href=cmdsea><a href="chap2.html#tag_001_009_001_001">
Command Search and Execution
</a></xref>.
<br>
</blockquote><hr size=2 noshade>
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UNIX &reg; is a registered Trademark of The Open Group.<br>
Copyright &copy; 1997 The Open Group
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